1. Field of the Invention
This invention relates to a fire alarm system, and more particularly to such a system which comprises a plurality of alarms which may be operated by an alarm loop, and which are subject to selective interrogation so as to feed an analog value of a particular fire characteristic to a central control, the analog value being tapped from a measuring transducer for that particular characteristic.
2. Description of the Prior Art
Fire alarm system are well known in the art and may be supplied by a commercial power supply or by batteries. In the event of a breakdown of the commercial supply, fire alarm systems are to be supplied for a minimum length of time by a second, independent energy source. Batteries generally serve this purpose. The requisite capacity of this emergency current supply is determined, on the one hand, by the current drain of the alarm central control, and, on the other hand, by the number of alarms connected to the central control.